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Steady state levels of nortriptyline as a function of the number of functional CYP2D6 genes Dalen et al

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CYP2D6 and the European population Too rapid drug metabolism No drug response at ordinary dosage Non responders Too slow drug metabolism Too high drug levels at ordinary dosage High risk for ADRs No response from certain prodrugs (e.g. codeine) 15-20 million people have CYP2D6 gene duplications (UMs) 20-30 million people have no CYP2D6 enzyme (PMs)